Mechanical parts having increased wear resistance

ABSTRACT

Borided parts for wear surfaces in equipment for use in earth boring, well completion and fluid extraction are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional patent applicationSer. No. 60/745,228, filed Apr. 20, 2006, the entirety of which ishereby incorporated herein by reference.

FIELD OF THE INVENTION

This invention pertains of borided parts for wear surfaces in equipmentfor use in earth boring, well completion and fluid extraction.

BACKGROUND OF THE INVENTION

Oil exploration is a specialized process that combines elegantscientific models and brute force prospecting. Seismic prospectingtechniques employ sound waves to find probable oil reserves thousands offeet below the Earth's surface, and sophisticated modeling techniquesare used to characterize the geology of those locations. Once a likelysite is identified, a hole is drilled into the ground until oil or gasis found or the driller decides to abandon the site for a likelierprospect. At some sites, the hole is drilled using a top head driveattached to a length of hollow pipe. As the hole becomes deeper, extrasections are added to the pipe. In addition, a continuous stream ofdrilling “mud,” an aqueous slurry containing clay and other chemicals,is pumped through the drill pipe and through holes in the drill bit tocool the bit. The mud also coats the side of the hole to preventcollapse and carries crushed rock to the surface. The mud is pumped intothe hole by a mud, or slush, pump.

The drill bit has to cut through rock and gradually wears. In addition,the mud and the cuttings traveling to the surface wear not only thedrill bit but components of the mud pump. Drilling (and mud pumping) isconducted 24 hours a day, but if any of the parts wear out, the entireoperation may need to be halted while the part is repaired. Thecomponents of the mud pump, located at the surface, are easilyaccessible. On the other hand, the entire length of thousands of feet ofhollow pipe have to be removed section by section to replace the drillbit. As a result, it is desirable to increase the useable lifetime ofall the wearing parts used in oil drilling.

DEFINITIONA

As used herein, the terms “boriding” and “boronizing” are usedinterchangeably and indicate the development of a boron-containing layeron a metal substrate, such that boron diffuses into the metal and reactswith a component of the metal or a component of the metal diffuses tothe boron-containing layer and reacts with the boron, or both.

As used herein, the term “fluid extraction” refers to the removal ofoil, natural gas, water, and/or other fluids from underground.

As used herein, the term “metallic” refers to a material that includesat least 50% metal elements (e.g., Fe, Ti, Zn, etc.) in a metallic,intermetallic, or alloy phase. In some embodiment, the material mayinclude at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% metal elements in a metallic, intermetallic, or alloy phase.

As used herein, the terms “mud pump” and “slush pump” are usedinterchangeably.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the several figures of thedrawing, in which,

FIG. 1 is an exploded view of a piston and liner for use in an exemplarymud pump (Gardner Denver Service Manual 15-504).

FIG. 2 is a cross-sectional view of an exemplary mud pump (GardnerDenver Service Manual 15-603, page 11)

FIG. 3 is an exploded view of a valve for use in an exemplary mud pump(Gardner Denver Service Manual 15-504 p 9).

FIGS. 4A and B are micrographs of cross-sections of two steel samplesafter boriding at A) 1700° F. for 8 hr and B) 1500° F. for 24 hr.

FIG. 5 is a graph illustrating the change of hardness (HV₅₀) with depthfor various borided components (1V and 2V: Valve bodies; 1S and 2S:Valve seats).

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION

In one embodiment, at least a first portion of a surface of a componentfor use in combination with a second component during earth-boring, wellcompletion (e.g., fracturing and cementing the well after drilling), orfluid extraction comprises a metallic material and is borided. Incertain embodiments, the borided portion does not wear against ametallic surface of the second component during use. In someembodiments, the component is not a tricone bit. The component may befabricated from a ferrous or non-ferrous metal or metal alloy. In someembodiments, the metal or metal alloy may be steel, titanium, or atitanium or chromium alloy. In certain embodiments, the first portion issubstantially metallic, or may be at least 80% metallic, at least 85%metallic, at least 90% metallic, or at least 95% metallic.

Various equipment for use in earth-boring, well completion, and fluidextraction can benefit from the teachings of the invention. Duringexploration and drilling for fluids such as oil, natural gas, and water,drilling hardware is subjected to abrasive, erosive, and corrosiveconditions. These wear modes reduce the useful life of hardwarecomponents and increase drill rig operating costs. The teeth of drillbits used in oil and gas exploration and drilling are often made fromcemented tungsten carbide, due to its resistance to abrasion anderosion. However, due to the difficult nature of working with tungstencarbide, fabrication of the teeth for drill bits is complex, laborintensive, and costly. Steel teeth, which are easier and less costly tofabricate, are sometimes used, however they may not be sufficientlywear-resistant for some applications. The surface of the drill bit, theroller cones to which the teeth are secured, and the nozzle from whichdrilling mud is directed into the drill hole are often fabricated fromsteel as well. Boriding can increase the wear resistance of all of thesecomponents, allowing them to be fabricated from steel or other metalsinstead of tungsten carbide or other cermets or metal-matrix composites.Wear also is a problem for many other components used in oil and gasdrilling, such as, for example, radial and thrust bearings, mechanicalcouplings, wear pads, flow diverters and restrictors, mud pump liners,and impellers.

Additional parts that may benefit from boriding include various fishingtools, apparatus to recover parts from within a bore. Because thesecomponents tap a thread in the component to secure themselves to thecomponent, they often can only be used once for a particular sizecomponent, after which the tap/thread is too worn to recover a secondcomponent of the same size. These tools are often tapered and thus canbe used to recover a component having a larger diameter even after thesmaller diameter regions become worn. However, boriding can harden thesurface sufficiently that the fishing tool can be used two or more timesto recover parts from a bore. Exemplary fishing tools include but arenot limited to spears, taper taps, and overshots.

Many other components of exploration and drilling equipment are subjectto wear by corrosion, abrasion, or erosion, including, for example,radial and thrust bearings, mechanical couplings, wear pads, flowdiverters and restrictors, mud and cement pump liners and impellers,drill pipes, valves, directional drilling assemblies, hanger assemblies,fishing tools (e.g., spears, taper taps, and overshots), percussionassemblies, nozzles, and core lifters. Many different coating methodshave been tried for improving the abrasion and corrosion resistance ofthese components. These include thermal spraying and application carbidecomposite coatings, as well as nickel and chrome plating. While thesecoatings can improve the life of the part, further improvements canprovide dramatic decreases in downtime and replacement costs.

During earth-boring, mud pumps are used to circulate pumping mud in thedrill hole as the mud carries cuttings to the surface. The extent andmode of wear to the pump components is determined by the abrasiveness,particle concentration, particle size, velocity, pH, and othercharacteristics of the particles and the fluid as well as the operatingconditions of the pump such as flow rate, pressure, etc. Depending onthe site, pumps may need to run continuously for weeks or months at atime. Wear results in part from the flow of particles within the mudabrading the surfaces of the pump's components. As the surfaces of thesecomponents wear away even a small amount, the ability of a pump tomaintain pressure and convey the pumping mud becomes greatly diminished.When pump components wear beyond a certain limit and begin to performbelow acceptable process limits, the pumps and/or process lines must beshut down and the components or entire pumps must be replaced.

In an exemplary embodiment, at least some of the metal bearing surfacesof a mud, or slush, pump are borided. FIG. 1 is an exploded view of anexemplary piston for use in an exemplary mud pump. Piston rod 1, pumpliner 5, and piston hub 6 all have metal bearing surfaces. FIG. 2 is across-sectional view of a mud pump. In addition to the piston and itsassociated components, the pump also includes two valves 20, shown inexploded view in FIG. 3. Both valve body 23 and valve seat 24 havemetallic bearing surfaces. It is contemplated that all of thesecomponents can experience improved tribological properties andperformance as a result of boriding.

It is contemplated that other components employed in earth-boring, wellcompletion, and fluid extraction may also benefit from boriding. Forexample, DTH (down the hole) hammer bits wear against rock as they drillthe well, while the internal components of the hammers wear against eachother. While these hammer bits often have carbide inserts, it iscontemplated that the lifetime of the metallic portions of the hammerbit may also be extended by boriding. Fracturing tubes may be abradedand/or corroded by the fracturing fluid. Valve seats and valve bodiesabrade against the pumping mud but also against each other. Drill pipesare initially abraded by the pumping mud, foam (air drilling), brine,and the rock it carries out of the well and later by fluids beingextracted by the well and any particulate matter they carry. Drill pipesmay also be corroded by fluids such as water that are pumped into thewell. Abrasion of core lifters can reduce the length of cores that canbe cut and brought to the surface and, in extreme cases, can jeopardizethe cohesion of the core sample, making recovery difficult. Directionaldrilling assemblies may experience uneven wear as a result of thedeviation of the drilling direction from the vertical. Plungers forcement pumps abrade against the rocks in the cement and are alsochemically eroded by the elevated pH of lime-based materials. Flowdiverters and flow restrictors may wear not only from particulates inthe extracted fluid but also from the fluid itself. It is contemplatedthat boriding of radial and thrust bearings may not only reduce wear butmay also reduce fatigue by reducing friction during use. Additionalparts that may benefit from boriding include but are not limited tomechanical couplings, wear pads, impellers, hanger assemblies,percussion assemblies, nozzles, rollers, cams, and shafts.

As discussed above, the lifetime of drilling and pump parts that areconstantly abraded by rock from a well is determined in part by thetribological properties of the components. The use of diffusion-basedtreatments such as nitriding, carburization, and boriding to increasesurface hardness and resistance to wear is well known. Boriding canproduce a harder surface than nitriding or carburization and is suitablefor some steel alloys for which nitriding or carburization are lessoptimal. Boriding also improves the corrosion resistance and reduces thecoefficient of friction more than carburization, increasing the lifetimeof parts. Even a 10% improvement in part life can create immense savingsover the course of drilling and completing a single well. Othertechniques for increasing surface hardness include the simple depositionof a boron-containing layer at the surface of a material. For example,electrochemistry may be employed to form a layer of iron boride at thesurface of a component. Alternatively, superabrasive compositesincluding materials such as diamond or cubic boron nitride may beelectroplated onto metallic components, or metal/metal boride mixturesmay be thermally sprayed onto components. However, layers formed bythese methods may not be chemically or mechanically integrated with thebulk material. Boriding provides greater integration of theboron-containing layer with the substrate. This integration increasesthe strength of the interface between the boride-containing layer andthe substrate, further reducing galling, tearing, seizing, and otherforms of wear in which a material flakes from the surface.

A variety of boriding techniques may be used to improve the tribology ofwearing parts for use in earth-boring, well completion, and fluidextraction. In some embodiments, boriding includes two processes: thegeneration of a thin boride layer at the surface of the material and thegrowth of that layer by diffusion into the bulk material. In some cases,the depth of the boron-containing diffusion zone may be over seven timesthicker than the surface boride layer (ASM Handbook, Volume 4, ASMInternational, Materials Park, Ohio, 1994). The diffusion layerincreases the resistance of the layer to delamination and also helpsreduce cracking resulting from differential rates of thermal expansionduring processing. In addition, diffusion of the boron into the bulkmaterial may improve the fatigue performance of the component.

An exemplary boriding method is pack boriding. A boron-containing powderis packed around a workpiece in a refractory container and heated.Alternatively, a paste may be applied to the workpiece and heated, or afluidized bed may be employed. In another embodiment, boriding may beperformed with a gas or plasma, allowing the boriding to be performedwithout annealing the core of the work piece, which can lead to graincoarsening and softening of the base material. Plasma boriding alsoallows quicker diffusion of reactive elements and higher velocity impactof reactive boron species against the surface of the workpiece. In someembodiments, it may be desirable to have a hardened surface around amore malleable core. The surface heating imposed during plasma boridingallows the difference in mechanical properties between the variousregions of the part to be maintained. Exemplary boriding methods aredisclosed in U.S. Pat. Nos. 3,926,327, 4,610,437, 4,637,837, and6,783,794. In another embodiment, a potassium haloborate may bedecomposed to the potassium halide salt and the boron trihalide, whichis then fed into an inert gas stream for plasma boriding. In oneembodiment, the potassium haloborate is potassium fluoroborate. It iscontemplated that this technique facilitates boriding of larger partsmore cheaply and safely than plasma boriding techniques employingorganoborates or boron halides.

It is contemplated that use of boriding to surface harden componentsallows them to be made from materials that are not traditionallyemployed in earth-boring. For example, pump liners are often fabricatedfrom chromium-containing steels. However, the use of a borided surfacemay enable these components to be fabricated from chromium alloys,titanium, and titanium alloys, for example, Ti-6Al-4V, Ti-6Al-6V-2Sn,Ti-10V-2Fe-3Al, Ti-0.3Mo-0.8Ni, Ti-0.2Pd, etc. TiB₂ has a hardness of3300 vickers, which can greatly improve the lifetime of componentsfabricated from borided titanium-containing metals.

In another embodiment, a system for preparing a well for fluidextraction includes a first component having a surface, at least a firstportion of which comprises a metallic material that is borided. Incertain embodiments, the system further includes a second componenthaving a metallic portion, and the first portion does not wear againstthe metallic portion during use. In certain embodiments, the componentis not a tricone bit. In certain embodiments, the system includes adrill, a mud pump, a cement pump, and/or a fracturing tube. The systemmay also include segments of a well liner.

In a further embodiment, a method of preparing a component for wearingagainst a material transported during earth-boring, well completion, orfluid extraction, the component having a surface, at least a portion ofwhich comprises a metallic material, includes boriding at least thefirst portion. In certain embodiments, the component is not a triconebit.

In a further embodiment, at least a first portion of an interior surfaceof a pump liner for use in earth-boring, well completion, or fluidextraction is borided. In another embodiment, a first portion of asurface of a component for use in earth-boring, well completion, orfluid extraction includes a substantially metallic material that isborided. According to another embodiment of the invention, the componentis a valve seat, valve body, mud pump liner, piston hub, sucker rod,piston rod, fishing tool, or plunger.

EXEMPLIFICATION EXAMPLE 1 Boronization of Valve Seat and Valve Body

A valve seat and valve body were borided by pack boriding. One samplewas borided for 8 hours at 1700° F.; the second was treated for 24 hoursat 1500° F. Micrographs of the boride layer, showing the sawtoothpattern frequently observed in borided steels, are shown in FIGS. 4A andB. The sample treated at 1700° F. had a solid boride layer of 0.0041″and a total boride layer depth of 0.0064″. The sample treated at 1500°F. had a solid boride layer of 0.0037″ and a total boride layer depth of0.0046″. HV₂₅ was measured (ASTM E 384-99^(E1), Vickers indenter, 50 gload) at a depth of 0.002″ below the surface and was 2018 and 1926 forthe samples treated at 1700° and 1500°, respectively, while HV₅₀₀measured at the (unborided) core was 156 and 162, respectively, animprovement of about 12-13%. FIG. 5 is a graph of HV₅₀ for borided valvebodies, seats, and a liner, measured across a cross section of a sampleprepared to a 1 micron final polish.

EXAMPLE 2 Field Testing of Boronized Valve Seat and Valve Body

Four borided valve bodies and valve seats, with urethane insert, as wellas four non-borided valve bodies and valve seats (control), withurethane inserts, were installed on a Continental Emsco DB 550 Duplexmud pump. The pump was run under normal operating conditions for fourmonths, at which point the non-borided parts had to be replaced. Theborided parts continued to work effectively.

Other embodiments of the invention will be apparent to those skilled inthe art from a consideration of the specification or practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with the true scope and spiritof the invention being indicated by the following claims.

1. A component for use in combination with at least a second componentduring earth-boring, well completion, or fluid extraction, the componenthaving a surface, at least a first portion of which comprises a boridedmetallic material, and wherein said first portion does not wear againsta metallic surface of the second component during use.
 2. The componentof claim 1, wherein the component is selected from a component of a mudpump or cement pump.
 3. The component of claim 1, wherein the componentis selected from a mud pump liner, a valve seat, a valve body, a pistonhub, a piston rod and a plunger.
 4. The component of claim 1, whereinthe component is a DTH hammer bit, fracturing tube, drill bit, radialbearing, thrust bearing, mechanical coupling, wear pad, flow diverter,flow restrictor, impeller, drill pipe, valve, directional drillingassembly, hanger assembly, percussion assembly, nozzle, or core lifter.5. The component of claim 1, wherein the component is a roller, cam,shaft, or pipe.
 6. The component of claim 1, wherein the metallicmaterial is selected from a ferrous metal, non-ferrous metal, ferrousmetal alloy, and non-ferrous metal alloy.
 7. The component of claim 6,wherein the metallic material is a steel.
 8. The component of claim 6,wherein the substantially metallic material is titanium, a titaniumalloy, or a chromium alloy.
 9. A system for preparing a well for fluidextraction, comprising: a first component having a surface, at least afirst portion of which comprises a borided metallic material; and asecond component having a metallic portion, wherein said first portiondoes not wear against said metallic portion during use.
 10. The systemof claim 9, wherein the system comprises a drill and a mud pump.
 11. Thesystem of claim 10, further comprising a mud pump liner.
 12. The systemof claim 9, wherein the system comprises a cement pump.
 13. The systemof claim 9, wherein the system comprises a fracturing tube.
 14. Thesystem of claim 9, wherein the first component is selected from acomponent of a mud pump or cement pump.
 15. The system of claim 9,wherein the first component is selected from a mud pump liner, a valveseat, a valve body, a piston hub, a piston rod, and a plunger.
 16. Thesystem of claim 9, wherein the first component is a DTH hammer bit,fracturing tube, drill bit, radial bearing, thrust bearing, mechanicalcoupling, wear pad, flow diverter, flow restrictor, impeller, drillpipe, valve, directional drilling assembly, hanger assembly, percussionassembly, nozzle, or core lifter.
 17. The system of claim 9, wherein thefirst component is a roller, cam, shaft, or pipe.
 18. The system ofclaim 9, wherein the substantially metallic material is selected from aferrous metal, non-ferrous metal, ferrous metal alloy, and non-ferrousmetal alloy.
 19. The system of claim 18, wherein the substantiallymetallic material is a steel.
 20. The system of claim 18, wherein thesubstantially metallic material is titanium, a titanium alloy, or achromium alloy.
 21. A method of preparing a component for wearingagainst a material transported during earth-boring, well completion, orfluid extraction, the component having a surface, at least a firstportion of which comprises a metallic material, the method comprising:boriding at least the first portion.
 22. The method of claim 21, whereinthe component is selected from a component of a mud pump or cement pump.23. The method of claim 21, wherein the component is selected from a mudpump liner, a valve seat, a valve body, a piston hub, a piston rod, anda plunger.
 24. The method of claim 21, wherein the component is a DTHhammer bit, fracturing tube, drill bit, radial bearing, thrust bearing,mechanical coupling, wear pad, flow diverter, flow restrictor, impeller,drill pipe, valve, directional drilling assembly, hanger assembly,percussion assembly, nozzle, or core lifter.
 25. The method of claim 21,wherein the component is a roller, cam, shaft, or pipe.
 26. The methodof claim 21, wherein the component is a fishing tool or sucker rod. 27.The method of claim 26, wherein the fishing tool is a spear, taper tap,or overshot
 28. The method of claim 21, wherein the substantiallymetallic material is selected from a ferrous metal, non-ferrous metal,ferrous metal alloy, and non-ferrous metal alloy.
 29. The method ofclaim 28, wherein the substantially metallic material is a steel. 30.The method of claim 28, wherein the substantially metallic material istitanium, a titanium alloy, or a chromium alloy.
 31. A pump liner foruse in earth-boring, well completion, or fluid extraction, wherein atleast a first portion of an interior surface of the pump liner isborided.
 32. The pump liner of claim 31, wherein the pump liner isfabricated from a ferrous metal, non-ferrous metal, ferrous metal alloy,or non-ferrous metal alloy.
 33. The pump liner of claim 32, wherein thepump liner is fabricated from titanium, a titanium alloy, or a chromiumalloy.
 34. A component for use in earth-boring, well completion, orfluid extraction, the component having a surface, at least a firstportion of which comprises a borided metallic material, and wherein thecomponent is selected from a mud pump liner, valve seat, a valve body, apiston hub, a piston rod, a plunger, sucker rod, and a fishing tool. 35.The component of claim 34, wherein the fishing tool is a spear, tapertap, or overshot.